I liked it. I'd give it an 8, and would see it again.
Ancient Greece fascinates me.

And yes, the casting was very good. Brad Pitt deserves accolades for training for this film. He quit smoking and had a new diet and workout plan for a year. The film was shot in Malta and Mexico, and he refused to turn the AC on, even on 100 degree nights....
He wanted to be at the top of his game and he pulled it off.

He was also concerned with the message the film conveyed. That violence and retribution are empty dead ends.
He says "It's about one civilization trying to overthrow another civilization. We can't be drawing these boundaries, us versus them. We've got to accept our common humanity. The things that separate us, they die. The thing that's everlasting is our humanity".

The crux of the war can be seen when Agamemnon and Menelaeus have just been offered an easy solution before both troops engage in battle. It would have been simple to agree.
But Agamemnon wanted the kingdom of Troy to add another conquest to his power of expansion and his brother wanted his manhood affirmed by destroying the man who took his wife away. Two old men, fighting for things that didn't belong to them.
And you know who survived.

Fools, .......wars are fought for ego.